WO2018001741A1

WO2018001741A1 - Injector for injecting a fluid, having a tapered inlet region of a passage opening

Info

Publication number: WO2018001741A1
Application number: PCT/EP2017/064584
Authority: WO
Inventors: Philipp Rogler; Dietmar Schmieder
Original assignee: Robert Bosch Gmbh
Priority date: 2016-06-29
Filing date: 2017-06-14
Publication date: 2018-01-04
Also published as: KR20190020703A; JP6824300B2; US11560868B2; DE102016211688A1; US20190309720A1; JP2019525054A; KR102453447B1

Abstract

The invention relates to an injector for injecting a fluid, comprising a valve seat (3), on which a sealing region is arranged; a closing element (5), which is arranged on an injector center axis (X-X) and which opens and closes at least one passage opening (30) on the valve seat (3); wherein the at least one passage opening (30) has a main axis (300) at a setting angle (ß) to the injector center axis (X-X); wherein the at least one passage opening (30) has an inlet region (41), and wherein the inlet region (41) is tapered.

Description

Description title

Injector for injecting a fluid with a tapering inflow region of a passage opening

State of the art

The present invention relates to an injector for injecting a fluid, in particular a fuel, with a reduced pressure drop and a self-centering closing element of a valve seat.

Injectors that inject liquids into a volume space, such as fuels in an internal combustion engine, are known. Conventional designs comprise housings with movable closing elements which are shaped precisely to a respective valve seat, for example a valve needle, for opening and closing the injector, for example controlled by a piezoelectric actuator or an electromagnet as solenoid valve.

It is also part of the state of the art of injection that the fluid is injected into a combustion chamber via a plurality of through openings, which are released by an inwardly opening valve needle. In the

Combustion chamber is formed and ignited an ignitable air-fuel mixture.

Manufacturing-related reasons require that the intended

Through holes are made conventionally from the outside of the injector to the inside, for example laser drilled or eroded. This creates production-related sharp-edged inside the

Through holes, resulting in consequence to disadvantageously high flow losses with a high pressure drop. Furthermore, this can be, not least in the

Application of a high-pressure injection to deviations from an ideally centric as possible run of the movable closing element and lead to its decentration, in particular to a drift. Even slightest deviations or inclinations in the injector can do so

Fluctuation behavior and not optimal spray images of the injected fluid lead. This has a detrimental effect on emissions and consumption, for example in the case of a fuel.

Furthermore, it has been found that a decentration, in particular a drift, of the movable closing element negatively influences the wear behavior of the injector.

Disclosure of the invention

The injector according to the invention for injecting a fluid, in particular a fuel, with the features of claim 1 has the advantage that reduced flow losses with a reduced pressure drop and a self-centering closing behavior of the closing element of the valve seat are possible. This can ensure that one is too strong

Wearful running of the closing element can be avoided.

Also, a spray image to be achieved in a volume space,

in particular in a combustion chamber, injected fluids with significantly higher and with smaller deviations from the desired behavior in terms

Drop size distributions and trajectories are met. Thus, the present invention has the advantage of favorably influencing the hydrodynamic conditions in the region of the injection, in order to optimize the inflow behavior and / or the spraying of the fluid injected downstream of the valve seat.

In the case of a preferred fuel injector, this also has a favorable effect on the operating behavior of the internal combustion engine and on a significant reduction of emissions. Furthermore, extend

Maintenance intervals and service lives very positive.

All of these advantages are achieved by an injector according to the invention for injecting a fluid, which comprises a valve seat, on which a sealing area is arranged, and a closing element. In this case, the closing element, for example a linearly movable valve needle, is arranged on an injector center axis and is moved to at least one valve seat Through hole, often a geometric arrangement of several through holes, release and re-close. In this case, the at least one passage opening has a main axis in one

Angle of inclination to the injector center axis. Furthermore, the at least one through-opening has an inflow region, wherein the inflow region is designed to be tapered.

The dependent claims show preferred developments of the invention. A preferred embodiment provides that a flow cross-section of the inflow region lying transversely to the main axis decreases continuously in the flow direction. On the other hand, it may just as well be preferred that there is at least one section in an inflow area tapering overall in the flow direction from the front to the rear, in which the

Flow cross section remains constant, so that in this respective

Section results in a cylindrical circumferential shape of the overall tapered inflow. In addition or as an alternative, the inflow region tapering overall in the flow direction can also be profiled

Have inner peripheral surface, for example, a wavy and or staircase running.

Preferably, the inflow region, as in a funnel, as a

Inner hollow cone with a cone angle α of the inner wall to a

Be executed cone central axis. Even in such a case, it may be provided that the inner peripheral surface of such a hollow inner cone could be designed not only smooth, but also profiled.

Furthermore, the cone central axis preferably intersects the main axis of the through opening in a tilt angle δ.

In the geometrically simplest case, which should not be regarded as limiting the invention, preferably fall the Kegelmittelachse and the

Main axis of the passage opening together. This corresponds to a zero tilt angle δ. In such a possible embodiment results in section with a plane E1, which by definition in the context of this

Invention is spanned by the inlet flow cross section of the inflow, a round entrance circumferential contour in this same plane El Thus, a circle center of the round entrance circumferential contour lies in

Intersection of the cone central axis and the major axis with the plane E1.

This results in further multiple benefits to different aspects of the performance of the injector itself and the downstream

taking place, in particular on the hydrodynamic and / or thermal and / or mechanical, processes.

Furthermore, the entry flow cross-section of the inflow region defining a plane E1 can have an entry circumferential contour in this same plane, plane E1, which preferably does not just turn out to be round. In principle, all types of non-circular entrance peripheral contours are executable. Because in modern 3D-controlled mechanical production machines, several degrees of freedom of the tools carrying out the contour can be controlled separately. The contour-executing tools are within the scope of the invention in addition to those known in the art

cutting tools, such as milling heads, on

Erosion dies, erosion wires and / or laser treatments.

By using the 3D degrees of freedom and non-circular circumferential contours are displayed, which are characterized not only by convex, but also by concave sub-areas.

In particularly preferred embodiments of a non-circular entry peripheral contour, this is oval in the plane E1.

This can result in a preferred embodiment with the geometric constellation of a rotationally symmetrical inner hollow cone by its employment to the main axis of the passage opening by a tilt angle δ. Because then correspond to the oval receiving contour of the sectional image in the plane E1.

However, in other embodiments, it may alternatively also be preferred that the inner hollow cone is not rotationally symmetrical to a cone central axis, but asymmetrical and not designed with a constant cone angle α of the inner wall. On the other hand, it may be preferred that the inner hollow cone comprises different sections of the inner wall with varied cone angles α. These sections of the inner wall can be defined as a function of the angle of the circle as follows.

Namely, on the entrance peripheral contour in the plane E1, a first circumferential point A closest to the main axis of the through-hole is first determined, for which a circular angle γ in the plane E1 around the main axis is defined equal to zero. Thus, the first circumferential point A serves as an initial coordinate for the circular angle γ, for example in a clockwise direction about the main axis.

Preferred embodiments provide that the cone angle α with the

Circular angle γ is made variable.

In the case of a non-circular entrance peripheral contour, it must then further at least one second to the main axis of the passage opening farthest

Give the circumference point B. Depending on the embodiment, this can be arranged at any desired circle angle γ relative to the first circumferential point A in the plane E1. In particularly preferred embodiments, the second circumferential point B is at the first circumferential point A in a circular angle γ equal to 180 °.

It may further preferably be provided that the inflow region is designed in the form of an asymmetrically distorted hollow hollow cone.

This is a further preferred embodiment in that at least a first, convex, i. with an increasing cone angle a, executed partial section, for example in the circular angular segment between the first peripheral point A and the second peripheral point B, at least one further, concave, i. followed by a decreasing cone angle a, executed section.

The further subsection may be, for example, as a single further subsection between the second circumferential point B and the first

Perimeter point A close the perimeter to a complete circle. Alternatively, the other, starting in the second peripheral point B can

Subsection further convex or concave executed sections follow. Thereby, a further preferred embodiment for a with the

Circle angle γ variable inlet circumferential contour of the inflow in the plane E1 described.

According to an advantageous development, the passage opening is divided into discrete areas, which are characterized by different flow cross sections. This can be in even more targeted form on the flow through the entire passage opening, downstream of the tapered

Einströmbereichs be taken to increase the disadvantages in the prior art influence.

Preferably, the passage opening in the flow direction downstream of the inflow region thus comprises an intermediate flow region with an intermediate flow cross section. Furthermore, the through-opening preferably comprises an outlet flow region with an outlet flow cross-section downstream of the intermediate flow region.

It is particularly preferred that the narrowest flow cross-section of the passage opening is placed in the region of the intermediate flow cross-section.

Preferably, the intermediate flow area and / or the outlet flow area is cylindrical to the main axis. This is an advantage for a cylindrical design in the simple production, for example, with a rotating drill or milling head.

However, this is not to be regarded as limiting the invention. Because it may just as well, in particular depending on the rheology of the fluid to be injected, be preferred that the intermediate flow region and / or the

Outflow flow area with variable flow cross-sections, esp. Rejuvenating or on the contrary straight again widening executed.

Furthermore, the dimensioning of the areas with different

Flow cross sections in relation to each other varied, yet targeted, designed. Preferably, therefore, the inflow region defines an inflow length, the interflow region an intermediate length, and the exit flow region an exit length. Thus, it may be particularly preferred that the inflow length and the intermediate length are similar to each other or the same length. Additionally or alternatively, the exit length may be greater than the inflow length and / or the intermediate length. In this case, the relation of the exit length to at least one such last-mentioned length can be selected in particular by a factor of 1.3 to 2.3, more preferably by 1.4 to 1.7.

The injector according to the invention is particularly preferably a fuel injector for injecting a fuel, in particular a liquid fuel.

drawing

Hereinafter, a preferred embodiment of the invention will be described in detail with reference to the accompanying drawings. In the drawing: is a schematic sectional view of an injector according to a preferred embodiment of the invention, a schematic, enlarged sectional view of a

Valve seat of the injector of Figure 1 with included

Through holes, a schematic, enlarged sectional view of a

Through hole of Figure 2, and a schematic plan view in the flow direction to an inflow region of the through hole of Figure 3.

Embodiment of the invention

Identical reference numbers refer to the same elements in the various figures. As can be seen from FIGS. 1 and 2, an injector 1 according to a preferred exemplary embodiment of the invention comprises a valve housing 2 and a valve seat 3. The valve seat 3 is fixed to the valve housing 2 by means of a, for example, positive connection.

The injector further comprises a closing element 5, in this preferred

Embodiment in the form of a linearly movable in the axial direction of the injector along a Injektormittelachse X-X valve needle. Furthermore, the injector 1 also comprises a restoring element 6, in this embodiment in the form of a mechanical spring, which holds the closing element 5 in the closed position shown in FIG.

The closing element 5 is actuated by means of an actuator 7, in this embodiment of a magnetic actuator. Reference numeral 8 denotes an electrical connection.

Fuel is guided in the interior of the injector 1 to the end of the closing element 5 on the valve seat 3.

In the figures 1 and 2, the valve seat 3 is arranged in front of a (not shown here) free injection volume, for example, to a combustion chamber, in which the fluid to be injected, for example a

Fuel is injected in the non-closed valve state.

As can be seen in particular from FIG. 2, the valve seat 3 is provided with a plurality of passage openings 30, which can be released and closed by the closing element 5 on a sealing seat 50. Like FIG. 1, FIG. 2 also shows the closed state of the injector.

As further seen in Figure 2, in this embodiment, the sealing seat 50 in the valve seat 3, on the injection side, here as a valve ball

executed, the end of the closing element 5, in addition to a narrow-volume fluid reservoir area 40. In this case, the fluid reservoir region 40 is designed as an area which is recessed into the sealing seat 50 in a flat manner

The optionally provided fluid reservoir area 40 serves primarily for

Afterflow of a thin fluid film. As a result, in particular one consistent wetting and a more uniform local pressure behavior guaranteed.

In this cross section shown here, two passage openings 30 can be seen in the illustrated sectional plane of the cross-sectional view, which corresponds to a basically possible embodiment.

In this case, the two passage openings 30 have a respective main axis 300.

With the main axis 300, the passage openings 30 to the

Injector center axis X-X of the injector with a pitch angle ß employed. In the embodiment shown here, the setting angle β for both recognizable passage openings 30 is equal to 30 °.

However, basically at least one or even each of the

Through holes 30 be aligned in a different angle ß.

The passage openings 30 are flowed through in a respective flow direction 200 by the fluid to be injected, see FIGS. 2 and 3.

The individual, generated by through hole 30 (not shown here) rays of liquid are usually formed due to

Zerwellungseffekten their flow outlet by stall from the respective circumferential inner walls and outlet edges as so-called spray lobes of finest primary and secondary drops.

FIG. 3 illustrates a passage opening 30 as a detail from FIG. 2 in the manner of a schematic sectional view. FIG. 4, which is assigned to FIG. 3, again shows the corresponding supervisory projection onto the through bore 30 arranged in the sealing seat 50, viewed in the direction of flow 200.

The geometric arrangement, in particular with respect to respective

Employment angle ß, and the inner configuration of the through holes 30 hydrodynamically influence the flow behavior of the fluid through the through holes 30 and downstream of its injection behavior. As in particular with reference to the preferred shown in Figure 3

Embodiment of a through hole 30 can be seen, the respective inner flow cross sections 550 along the flow direction 200 are variable.

And here are a total of four, by different

Different flow cross sections, discrete flow regions 40, 41, 42, 43 to differentiate.

On the one hand, the passage opening 30 is placed in the preferably existing fluid reservoir area 40.

In this case, the fluid reservoir region 40 is sunk into the sealing seat 50 in the form of a flat, convex depression, resulting in a fluid reservoir length L0 corresponding to the depression depth along the main axis 300 of the passage opening 30.

Orthogonal to the main axis 300, a sectional plane designated as plane E2 of the fluid reservoir region 40 can be seen in the sealing seat 50, in which a fluid reservoir flow cross section 500 lies.

The fluid reservoir flow cross section 500 marks at its circumference in the plane E2 a fluid reservoir circumferential contour 600.

On the other hand, it can be seen in FIG. 3 that the passage opening 30 itself is to be subdivided into its own three flow areas 41, 42, 43.

Thus, the through hole 30 shown in FIG

Flow direction 200 downstream of the fluid reservoir region 40 a

Inflow region 41 with an inlet flow cross-section 501.

By definition, the inlet flow cross-section 501 of the inflow region 41 comes to rest through the valve seat 3 in a sectional plane designated as plane E1. The plane E1 denotes a plane offset in parallel downstream of the plane E2, which plane is thus likewise spanned orthogonally to the main axis 300. In the plane E1, the inlet flow cross-section 501 describes at its periphery an inlet circumferential contour 601 of the inflow region 41. It should be noted at this point that at least one inner body edge of the

Through opening 30, in particular arranged in the inflow 41 and / or fluid reservoir area 40, in particular at least one

Circumferential contour 600, 601, 602, may be provided with a small radius and / or a 45 ° bevel. A thus further rounded flow passage area serves to reduce hydrodynamically unwanted effects such as

Stall and or cavitation.

In the preferred embodiment shown in FIGS. 3 and 4, the inlet flow cross section 501 of the inflow region 41 is smaller than the fluid reservoir flow cross section 500 of the fluid reservoir region 40.

Furthermore, in the direction of projection to the main axis 300, the inlet flow cross section 501 completely falls into the larger fluid reservoir flow cross section 500, so that the circumferential contours 600 and 601 do not cut through.

It should be noted at this point that this geometric constellation is not to be regarded as limiting the invention. However, in further preferred embodiments, the inlet flow cross-section 501 falls into the larger fluid reservoir flow cross-section 500 at least to a predominant area proportion, preferably greater than 90%.

Furthermore, the passage opening 30 in the flow direction 200 downstream of the inflow region 41 comprises an intermediate flow region 42 with an intermediate flow cross section 502.

Furthermore, the passage opening 30 in the flow direction 200 downstream of the intermediate flow area 42 comprises an outlet flow area 43 with an outlet flow cross section 503.

As can be further seen from FIG. 3, an inflow length L1 results for the inflow region 41, an intermediate length L2 for the intermediate flow region 42, and an outlet length L3 for the outflow flow region 43. In this case, both the intermediate flow region 42 along the entire intermediate length L2 and the outlet flow region 43 along the entire outlet length L3 are designed cylindrically to the main axis.

Here, the narrowest flow cross-section 550 of the through-opening 30 lies in the intermediate flow region 42 and is thus determined by the intermediate flow cross-section 502.

In this respect, as can be seen particularly well from FIG. 3, in this preferred embodiment, the passage opening 30 in its flow region located downstream of the inflow flow region 41 can be designed as a typical round bore, which widens in its bore cross section through an inner shoulder in the flow direction 200.

In the preferred embodiment, the inflow length L1 and the fall

Inter-length L2 similar in size or equal to each other.

Furthermore, the exit length L3 is of the order of magnitude approximately equal to or identical to the total length of inlet length L1 and intermediate length L2 together.

According to the invention, a tapered design of the inflow region 41 of at least one through-opening 30 has proved to be particularly advantageous. Thus, for the same in Figures 1 to 3 shown

Through openings 30 can be seen that the inlet flow cross-section 501 is greater than the intermediate flow cross-section 502 downstream selected.

Furthermore, in the preferred embodiment shown here, it can be seen that the flow cross section 550 decreases continuously over the length L1, ie from the inlet flow cross section 501 to the intermediate flow cross section 502, with a linear gradient.

Thus, here, as can be seen in particular from FIG. 3, a funnel-shaped tapering inflow region 41 can be described as an inner hollow cone, defined by a cone angle α of the inner wall to form a central axis 800 of a cone. In particular, from Figure 3 shows that the above-described linear slope is determined not only by the cone angle α alone, but additionally by a tilt angle δ.

Because the tilt angle δ denotes the intersection angle between the

Taper central axis 800 and the main axis 300 of the through hole 30. Thus, the tilt angle δ is a measure of the employment of the inner hollow cone of the, in Fig. 3 funnel-shaped, tapered inflow region 41 to the main axis 300 of the through hole 30th

In particular, the cone angle α and the tilt angle δ are thus decisively determining the geometry of the tapered inflow 41 of the through hole 30 and thus for the inflow of the

fluid to be injected.

It should be noted that in an alternative, not shown here

Embodiment, the tilt angle δ may be selected to zero, so that the cone central axis 800 and the major axis 300 of the through hole 30 coincide. In such an alternative embodiment, a round entrance circumferential contour 601 of the inflow region 41 results in section with a plane E1 spanned by the inlet flow cross section 501. Then, a circle center M of the round entrance peripheral contour 601 lies at the intersection of the cone central axis 800 and the main axis 300 with the plane E1.

However, in FIG. 3, with the associated view of FIG. 4, there is a preferred embodiment in which the geometric constellation of a rotationally symmetrical inner hollow cone with an adjustment to the main axis of the passage opening is shown by a tilt angle δ of approximately ten angular degrees.

From the intersection of the obliquely set inner hollow cone with the plane E1 of the inlet flow cross section 501, an oval outgoing entry peripheral contour 601 is geometrically formed.

The resulting oval entry peripheral contour 601 is particularly well shown in FIG. Further, in the illustration of FIG. 4, the positions of two landmarks A, B as defined are noted along the entrance perimeter contour 601 which span the oval. On the one hand, this concerns a first circumferential point A closest to the main axis 300 of the passage opening 30.

On the other hand, a second circumferential point B, which is farthest from the main axis of the passage opening, is entered.

As can also be seen from FIG. 4, in the plane E1, an angular coordinate designated as a circle angle .gamma. Runs around the main axis 300 from the angle .alpha

Zero set first circumferential point A.

Thus, in the preferred embodiment, as indicated in Figure 4, the second circumferential point B to the first circumferential point A in a circular angle γ equal to 180 °.

Here is as a sense of rotation of the circular angle γ clockwise to the the

Main axis 300 marking center M registered.

It should be noted at this point in the description of the figures that further embodiments provide that the cone angle α is designed to be variable in relation to the circle angle with the circular angle γ. As a result, the tapered inflow area is then designed as a slanted inner hollow cone.

Claims

Injector for injecting a fluid, comprising:

a valve seat (3) on which a sealing region is arranged, and

a closing element (5) arranged on an injector center axis (X-X) which releases and closes at least one passage opening (30) on the valve seat (3),

wherein the at least one passage opening (30) has a main axis (300) at a setting angle (β) to the injector center axis (X-X),

wherein the at least one passage opening (30) has a

Inflow region (41), and

wherein the inflow region (41) is tapered.

Injector according to claim 1, wherein a transverse to the main axis (300) lying flow cross-section (501) of the inflow region (41) in

Flow direction (200) decreases continuously.

Injector according to claim 1 or 2, wherein the inflow region (41) is designed as an inner hollow cone (70) with a cone angle (a) of the inner wall to a Kegelmittelachse (800).

Injector according to one of the preceding claims, wherein the

Taper central axis (800) the main axis (300) of the through hole (30) in a tilt angle (δ) intersects.

Injector according to one of the preceding claims, wherein the inlet flow cross section (501) of the one defining a plane (E1)

Inflow region (41) has a non-circular entrance peripheral contour (601) in the plane (E1). An injector according to claim 5, wherein the entrance peripheral contour (601) in the plane (E1) is made oval.

An injector according to claim 6, wherein the entrance peripheral contour (601) in the plane (E1) comprises a first circumferential point (A) closest to the main axis (300) of the through-hole (30), which has a circular angle (γ) in the plane (E1 ) is defined about the major axis (100) equal to zero; and a second circumferential point (B) farthest from the main axis (300) of the through-hole (30), which is arranged at 180 ° in particular at a circular angle (γ); and wherein the cone angle (a) is made variable with the circular angle (γ).

Injector according to one of the preceding claims, wherein the

Through opening (30) in the flow direction (200) downstream of the

Inflow region (41) comprises an intermediate flow region (42) with an intermediate flow cross section (502) and downstream of the intermediate flow region (42) an outlet flow region (43) with an outlet flow cross section (503), wherein in particular the intermediate flow region (43) Flow cross-section (502) is the narrowest flow cross-section of the through hole (30).

An injector according to the preceding claim, wherein the intermediate flow area (42) and / or the exit flow area (43) is cylindrical to the main axis (300).

An injector according to claim 8 or 9, wherein said inflow portion (41) defines an inflow length (L1), said intermediate flow portion (42) defines an intermediate length (L2), and said exit flow portion (43) defines an exit length (L3); and wherein the inflow length (L1) and the intermediate length (L2) are similar or equal to each other and / or the exit length (L3) is greater than the inflow length (L1) and / or the intermediate length (L2 ) is, in particular about a factor of 1, 3 to 2.3, more preferably by 1, 4 to 1, 7.